1. Field of the Invention
The present invention pertains to fiber optics or photonics modules. More particularly, this invention relates to precisely erect a planar optical component (e.g., a mirror or an optical filter) on a mounting member.
2. Description of the Related Art
Optical communications systems are widely used for carrying very large amount of information with low error rate and at low cost over great distances. For this reason, considerable development has been done on components of optical communication systems, such as photonics packages or modules. Photonics generally refers to devices that share both electronic and optical attributes. These devices can be laser devices, which generate coherent light in response to an electronic signal, and photo detectors, which generate an electronic signal in response to light.
A typical photonics module such as the photonics module 10 of FIG. 1 uses edge emitting semiconductor lasers and surface detecting photo detectors. As can be seen from FIG. 1, since an edge emitting laser 11 has a relatively wide radiation angle, a lens 12 is typically inserted between the laser 11 and an optical fiber 13 to obtain high optical coupling efficiency. In addition, a lens 17 is typically inserted between the optical fiber 13 and a photo detector 15. The inserted lens 17 improves the optical coupling efficiency between the optical fiber 13 and the photo detector 15. Because the photonics module 10 can function, for example, as a bidirectional module, it may be desirable to insert an optical filter 18 in the photonics module 10 to direct light beams among the three elements 11, 13, and 15 for desired operation.
In making the photonics module 10, the laser 11, the lens 12, the optical filter 18, and the optical fiber 13 must be in precise predetermined alignment with one another. In addition, the optical fiber 13, the optical filter 18, the lens 17, and the photo detector 15 must be in precise predetermined alignment with one another. To achieve this, fixtures and/or mounts are typically needed to hold the components in place and in alignment with one another, as shown in FIG. 2.
As can be seen from FIG. 2, a fixture 21 is used to hold the lens 12 in place and in predetermined alignment with the laser 11 that is also mounted on the fixture 21. This fixture 21 is then coupled to another fixture 22 that holds the optical fiber 13 and the optical filter 18 in place. A third fixture 20 is used to hold the lens 17 in place and in alignment with the photo detector 15. The fixture 20 also mounts and secures the photo detector 15. Because the photo detector 15 is the surface detecting photo detector (as shown in FIG. 2), the photo detector 15 is mounted on the fixture 20 perpendicular to the incoming light, as shown in FIG. 2. The fixture 20 is also coupled to the fixture 22. The alignment of the laser 11, the lenses 12 and 17, the photo detector 15, the optical filter 18, and the optical fiber 13 is achieved by the fixtures 20 through 22.
One disadvantage of such photonics modules or packages is that the fixtures are typically relatively costly to fabricate because they typically require relatively high precision. Another disadvantage is that it is typically time consuming to assemble the photonics modules using the fixtures, thus causing low throughput. In addition, time may also be needed for alignment and adjustment during assembling the photonics modules. This typically hinders mass-production of the photonics modules by operators having a moderate level of skill while maintaining the required alignment criteria. These factors typically limit the cost reduction of the photonics modules.
Prior attempts have been made to mount a number of components (e.g., a laser and a spherical lens) on a single silicon mounting member. However, it is typically difficult to precisely mount a planar optical device such as the optical filter 10 of FIGS. 1-2 on a planar surface of a mounting member using conventional mounting mechanisms because it is difficult to define the three-dimensional location of the planar optical device on the planar surface of the mounting member. In addition, mounting the planar optical device on the planar surface of the mounting member requires active alignment and complex bonding and packaging steps.